Geometry Library Google Maps API V3

Node JS/ Javascript Geometry Library provides utility functions for the computation of geometric data on the surface of the Earth. Code ported from Google Maps Android API.

Features

• Spherical contains spherical geometry utilities allowing you to compute angles, distances and areas from latitudes and longitudes.
• Poly utility functions for computations involving polygons and polylines.
• Encoding utilities for polyline encoding and decoding.

Installation

Issue following command:

yarn add node-geometry-library

npm i node-geometry-library

Usage

Here is an example of using GeometryLibrary:

import {SphericalUtil, PolyUtil} from "node-geometry-library";

let response = SphericalUtil.computeHeading(
  {lat: 25.775, lng: -80.19}, // from object {lat, lng}
  {lat: 21.774, lng: -80.19} // to object {lat, lng}
);
console.log(response) // -180

let response = SphericalUtil.computeDistanceBetween(
  {lat: 25.775, lng: -80.19}, //from object {lat, lng}
  {lat: 21.774, lng: -80.19} // to object {lat, lng}
);

console.log(response) // 444891.52998049


let response =  PolyUtil.isLocationOnEdge(
  {lat: 25.774, lng: -80.19}, // point object {lat, lng}
  [
    // poligon arrays of object {lat, lng}
    {lat: 25.774, lng: -80.19},
    {lat: 18.466, lng: -66.118},
    {lat: 32.321, lng: -64.757}
  ]
);

console.log(response)  // true



let response =   PolyUtil.isLocationOnPath(
  {lat: 25.771, lng: -80.19}, // point object {lat, lng}
  [
    // poligon arrays of object {lat, lng}
    {lat: 25.774, lng: -80.19},
    {lat: 18.466, lng: -66.118},
    {lat: 32.321, lng: -64.757}
  ]
);

console.log(response) // true  

let response =  PolyUtil.containsLocation(
  {lat: 23.886, lng: -65.269}, // point object {lat, lng}
  [
    // poligon arrays of object {lat, lng}
    {lat: 25.774, lng: -80.19},
    {lat: 18.466, lng: -66.118},
    {lat: 32.321, lng: -64.757}
  ]
);

console.log(response) // false    

let response = PolyUtil.distanceToLine(
  {lat: 61.387002, lng: 23.890636}, // point object {lat, lng}
  {lat: 61.487002, lng: 23.790636}, // line startpoint object {lat, lng}
  {lat: 60.48047, lng: 22.052754} // line endpoint object {lat, lng}
);
console.log(response) // 12325.124046196 in meters

let response =  PolyUtil.encode([
  {lat: 38.5, lng: -120.2},
  {lat: 40.7, lng: -120.95},
  {lat: 43.252, lng: -126.453}
]);

console.log(response) // '_p~iF~ps|U_ulLnnqC_mqNvxq`@'


let response =  PolyUtil.decode('_p~iF~ps|U_ulLnnqC_mqNvxq`@');  

console.log(response) /**
  [ { lat: 38.5, lng: -120.2 },
    { lat: 40.7, lng: -120.95 },
    { lat: 43.252, lng: -126.453 }
  ]

  */

Available methods

PolyUtil class

• containsLocation(point, polygon, geodesic = false)
• isLocationOnEdge(point, polygon, tolerance = PolyUtil.DEFAULT_TOLERANCE, geodesic = true)
• isLocationOnPath(point, polyline, tolerance = PolyUtil.DEFAULT_TOLERANCE, geodesic = true)
• distanceToLine(p, start, end)
• decode(encodedPath)
• encode(path)

SphericalUtil class

• computeHeading(from, to)
• computeOffset(from, distance, heading)
• computeOffsetOrigin(to, distance, heading)
• interpolate(from, to, fraction)
• computeDistanceBetween( from, to)
• computeLength(path)
• computeArea(path)
• computeSignedArea(path)

containsLocation( point, polygon, geodesic = false ) - To find whether a given point falls within a polygon

• point - {'lat': 38.5, 'lng': -120.2}
• polygon - [ {'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95 }, {'lat': 43.252, 'lng': -126.453} ]
• geodesic - boolean

Returns boolean

const response =  PolyUtil.containsLocation(
              {'lat': 23.886, 'lng': -65.269}, // point object of {lat, lng}
             [ // poligon arrays of object {lat, lng}
                {'lat': 25.774, 'lng': -80.190},
                {'lat': 18.466, 'lng': -66.118},
                {'lat': 32.321, 'lng': -64.757}
             ]);  

console.log(response) // false

isLocationOnEdge( point, polygon, tolerance = PolyUtil.DEFAULT_TOLERANCE, geodesic = true ) - To determine whether a point falls on or near a polyline, or on or near the edge of a polygon, within a specified tolerance in meters.

• point - {'lat': 25.774, 'lng': -80.190}
• polygon - [{'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95}, {'lat': 43.252, 'lng': -126.453}]
• tolerance - tolerance value in degrees
• geodesic - boolean

Returns boolean

const response =  PolyUtil.isLocationOnEdge(
              {'lat': 25.774, 'lng': -80.190}, // point object {lat, lng}
              [ // poligon arrays of object {lat, lng}
                {'lat': 25.774, 'lng': -80.190},
                {'lat': 18.466, 'lng': -66.118},
                {'lat': 32.321, 'lng': -64.757}
              ])  ;

console.log(response) // true

isLocationOnPath( point, polygon, tolerance = PolyUtil.DEFAULT_TOLERANCE, geodesic = true ) - To determine whether a point falls on or near a polyline, within a specified tolerance in meters

• point - {'lat': 25.774, 'lng': -80.190}
• polygon - [{'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95}, {'lat': 43.252, 'lng': -126.453}]
• tolerance - tolerance value in degrees
• geodesic - boolean

Returns boolean

response = PolyUtil.isLocationOnPath(
              {'lat': 25.774, 'lng': -80.190}, // point object if {lat, lng}
              [ // poligon arrays of object {lat, lng}
                {'lat': 25.774, 'lng': -80.190},
                {'lat': 18.466, 'lng': -66.118},
                {'lat': 32.321, 'lng': -64.757}
              ])  ;

console.log(response) // true

distanceToLine( p, start, end ) - To calculate distance from a point to line start->end on sphere.

• p - {'lat': 61.387002, 'lng': 23.890636}
• start - {'lat': 61.487002, 'lng': 23.790636}
• end - {'lat': 60.48047, 'lng': 22.052754}

Returns distance from a point to line

const response = PolyUtil.distanceToLine(
              {'lat': 61.387002, 'lng': 23.890636}, // point object {lat, lng}
              {'lat': 61.487002, 'lng': 23.790636}, // line start point object {lat, lng}
              {'lat': 60.48047, 'lng': 22.052754}// line endpoint object {lat, lng}
             );  

console.log(response) // 12325.124046196 in meters

decode( encodedPath ) - Decodes an encoded path string into a sequence of LatLngs.

• encodedPath - string '_p~iF~ps|U_ulLnnqC_mqNvxq`@'

Returns array

const response = PolyUtil.decode('_p~iF~ps|U_ulLnnqC_mqNvxq`@');  

console.log(response);
/*
  [ { lat: 38.5, lng: -120.2 },
    { lat: 40.7, lng: -120.95 },
    { lat: 43.252, lng: -126.453 }
  ]

*/

encode( path ) - Encodes a sequence of LatLngs into an encoded path string.

• path - [ {'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95}, {'lat': 43.252, 'lng': -126.453} ]

Returns string

response =  PolyUtil.encode(
              [
                {'lat': 38.5, 'lng': -120.2},
                {'lat': 40.7, 'lng': -120.95},
                {'lat': 43.252, 'lng': -126.453}
              ]);

console.log(response); // '_p~iF~ps|U_ulLnnqC_mqNvxq`@'

computeHeading( from, to ) - Returns the heading from one LatLng to another LatLng.

• from - {'lat': 38.5, 'lng': -120.2}
• to - {'lat': 40.7, 'lng': -120.95}

Returns int

response =  SphericalUtil.computeHeading(
              {'lat': 25.775, 'lng': -80.190},
              {'lat': 21.774, 'lng': -80.190}));

console.log(response); // -180

computeOffset( from, distance, heading ) - Returns the LatLng resulting from moving a distance from an origin in the specified heading.

• from - {'lat': 38.5, 'lng': -120.2}
• distance - number, the distance to travel
• heading - number, the heading in degrees clockwise from north

Returns array

response =  SphericalUtil.computeOffset({'lat': 25.775, 'lng': -80.190}, 152, 120);

console.log(response);

/*
  {
    'lat': 25.774316510639,
    'lng': -80.188685385944
  }
*/

computeOffsetOrigin( from, distance, heading ) - Returns the location of origin when provided with a LatLng destination, meters travelled and original heading. Headings are expressed in degrees clockwise from North.

• from - {'lat': 38.5, 'lng': -120.2}
• distance - number, the distance to travel
• heading - number, the heading in degrees clockwise from north

Returns array

response =  SphericalUtil.computeOffsetOrigin({'lat': 25.775, 'lng': -80.190}, 152, 120);

console.log(response);
/*
  {
    'lat': 14.33435503928,
    'lng': -263248.24242931
  }
*/

interpolate( from, to, fraction ) - Returns the LatLng which lies the given fraction of the way between the origin LatLng and the destination LatLng.

• from - {'lat': 38.5, 'lng': -120.2}
• to - {'lat': 38.5, 'lng': -120.2}
• fraction - number, a fraction of the distance to travel

Returns array

response =  SphericalUtil.interpolate({'lat': 25.775, 'lng': -80.190}, {'lat':26.215, 'lng': -81.218}, 2);

console.log(response);
/*
    {
      'lat': 26.647635362403,
      'lng': -82.253737943391
    }
*/

computeDistanceBetween( from, to ) - Returns the distance, in meters, between two LatLngs. You can optionally specify a custom radius. The radius defaults to the radius of the Earth.

• from - {'lat': 38.5, 'lng': -120.2}
• to - {'lat': 38.5, 'lng': -120.2}

Returns float

response =  SphericalUtil.computeDistanceBetween({'lat': 25.775, 'lng': -80.190}, {'lat': 26.215, 'lng': -81.218});

console.log(response); //float 113797.92421349

computeLength( path ) - Returns the length of the given path, in meters, on Earth.

• path - [ {'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95}, {'lat': 43.252, 'lng': -126.453} ]

Returns float

const response =  SphericalUtil.computeLength([
                {'lat': 38.5, 'lng': -120.2},
                {'lat': 40.7, 'lng': -120.95},
                {'lat': 43.252, 'lng': -126.453}
              ]);

console.log(response); //float 788906.98459431

computeArea( path ) - Returns the area of a closed path.

• path - [ {'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95}, {'lat': 43.252, 'lng': -126.453} ]

Returns float

response =  SphericalUtil.computeArea([
                {'lat': 38.5, 'lng': -120.2},
                {'lat': 40.7, 'lng': -120.95},
                {'lat': 43.252, 'lng': -126.453}
              ]);

console.log(response); //float 44766785529.143

computeSignedArea( path ) - Returns the signed area of a closed path.

• path - [ {'lat': 38.5, 'lng': -120.2}, {'lat': 40.7, 'lng': -120.95}, {'lat': 43.252, 'lng': -126.453} ]

Returns float

response =  SphericalUtil.computeSignedArea([
                {'lat': 38.5, 'lng': -120.2},
                {'lat': 40.7, 'lng': -120.95},
                {'lat': 43.252, 'lng': -126.453}
              ]);

console.log(response); //float 44766785529.143

Credits

alexpechkarev

Support

Please open an issue on GitHub

License

Geometry Library Google Maps API V3 is released under the MIT License. See the bundled LICENSE file for details.